Sony has unveiled the latest version of its Reader digital book.

The handheld tablet is slightly smaller than a normal paperback, and has a 6in screen and weighs just 9oz.

Central to the device is a new E Ink display which Sony claims allows for a 180-degree viewing angle.

The screen is designed to mimic paper text, and will set the Reader apart from other electronic book devices, according to the company.

In addition to internal storage, users will be able to store books on SD memory and Memory Stick cards.

"Reader allows people to carry a wide variety of reading material whether they are on a flight, in a waiting room or outdoors," said Steve Dowdle, managing director at Sony UK.

"Reader can handle a stack of books as well as other documents such as PDFs or Word documents, yet offers a 'book-like' reading experience unavailable with other electronic devices."

The new version will go head-to-head with Amazon's Kindle device, which benefits from a connection to the retailer's huge online book service allowing users to purchase content directly from Amazon's Whispernet network.

Sony hopes to negate Kindle's content advantage by signing a deal with UK bookseller Waterstone's.

The high street retailer will open "tens of thousands" of titles from its e-book service for the Reader, affording a ready source of content.

"Waterstone's is very impressed with the Reader from Sony and we think our customers will be too," said Waterstone category manager Toby Bourne.

"It offers a new way of reading that is easy and convenient, and we are working with publishers to develop the best range of e-books we can to read on it."

Sony plans to ship the first of the new Reader units in early September. Waterstone's plans to begin accepting pre-orders for the device on 24 July.